All references disclosed herein are incorporated by reference.
Ionomeric resins (ionomers) are copolymers of an olefin such as ethylene and an unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, or maleic acid, and optionally softening monomers, that have at least some portion of the acidic groups in the copolymer neutralized with metal ions such as sodium, lithium, calcium, magnesium or zinc. Ionomers are thermoplastic resins exhibiting enhanced properties, e.g. improved resilience, stiffness, toughness, durability, etc., for golf ball cover construction over balata (see below). As a result of their resilience, toughness, durability and flight characteristics, various ionomeric resins sold by E. I. du Pont de Nemours and Company under the trademark “Surlyn®” and by the Exxon Corporation under the trademark “Escor®” and the tradename “lotek” have become materials of choice for the construction of golf ball covers over the traditional balata (natural or synthetic rubber) covers. The softer balata covers, although exhibiting enhanced playability properties, lack the durability and cut resistance necessary for repetitive play.
Thermoplastic elastomers include, for example, copolyetheresters copolyetheresteramides. Compositions including polyetherester elastomers comprising polytrimethylene ether ester soft segment and tetramethylene or trimethylene ester hard segments are described, for example, in U.S. Pat. Nos. 6,562,457; 6,599,625; 5,128,185; 4,937,314; and 4,906,729. In addition, polytrimethylene ether ester amides are described in U.S. Pat. No. 6,590,065.
1,3-Propanediol (“PDO”) is a versatile building block for making polymers. For example, poly(trimethylene terephthalate), or “PTT” is well known and commercially available as polymer or fiber, suitable for many end uses. Other polymers derived from PDO include polyethers and polyether based copolymers. Among these are polytrimethylene ether glycol (“PO3G”) and its block copolymer derivatives. PO3G is the low molecular weight polyether polyol produced from polycondensation of PDO and has been described in a number of patents and patent applications. PO3G has numerous uses, especially in thermoplastic elastomers, as well as in other applications. Heretofore PO3G derivatives have been primarily directed toward fiber applications due to superior tenacity and elongation properties, among others.
The golf ball industry has also developed golf ball covers formed from polyurethane compositions. These covers combine good scuff resistance and a softness that enables spin control and good playability. Because of this combination of desirable factors, a number of premium golf balls with polyurethane covers (e.g. Titleist's Pro V-1) are providing better play control for the more skilled player.
Polyurethanes and polyurethane-ureas derived from PO3G are described in U.S. Patent Application Publication No. 2004/0030060.
In addition to their improved durability, harder covers tend to minimize ball spin and enable the ball to travel more straight off the clubface. Although some golfers prefer golf balls that maximize distance and provide low spin characteristics, others prefer softer, more resilient golf balls that enable spin control. Because of the different preferences of golfers, it is desirable to continue developing golf balls that have the desired properties with increased durability and toughness. Thus, it would be useful to develop a material for golf ball covers, mantles, intermediate layers, etc. having a combination of degrees of hardness and resilience and good scuff resistance with improved heat stability and melt processibility.
Current commercial ionomers derived from dipolymers have properties that vary according to the type and amount of metal cations, molecular weight and composition of the base resin (i.e. relative content of ethylene and methacrylic and/or acrylic acid groups). Ionomers can also be modified by the addition of comonomers to modify their physical properties. For example, terpolymers made from an olefin such as ethylene, an unsaturated carboxylic acid and other comonomers such as alkyl (meth)acrylates provide softer resins which can be neutralized to form softer ionomers. Attempts to provide harder ionomers include using relatively high percentages of the carboxylic acid moieties in the copolymer. The ethylene acid copolymers with high levels of acid can be difficult to prepare in continuous polymerizers because of monomer-polymer phase separation. This difficulty can be avoided by use of “co-solvent technology” as described in U.S. Pat. No. 5,028,674 or by employing somewhat higher pressures than those at which copolymers with lower acid are typically prepared. Despite these expedients, there is an inherent limit to the amount of the carboxylic acid-containing moieties that can be incorporated as comonomers in ethylene acid copolymers.
Another way to modify the properties of a thermoplastic composition is by blending a thermoplastic resin such as an ethylene acid copolymer or ionomer with other components. This allows one to more easily modify the properties of a composition by manipulating the amount and type of modifiers present in the composition in addition to varying the percentages of the monomers in the copolymer. Furthermore, blending modifiers can allow for easier, lower cost manufacture of polymer compositions by allowing one to prepare fewer base resins that can be subsequently modified to obtain desired properties.
Alternatively, compositions can be modified by blending modifiers with one or more of the comonomers of the thermoset resin prior to mixing with the other comonomers. This allows one to modify the properties of a composition by manipulating the amount and type of modifiers present in the composition in addition to varying the percentages of the various comonomers that make up the copolymer. These methods are particularly useful for modifying copolyetheresters, copolyetheresteramides, polyurethanes and polyurethaneureas.
The present invention provides for thermoplastic or thermoset compositions that are tougher, stronger, and more scuff and abrasion resistant than typical thermoplastic compositions by the incorporation of organic fiber micropulp as a modifier and their use in articles such as golf balls.
U.S. patent application Ser. No. 10/295,455 filed Nov. 15, 2002, relates to a process for producing organic fiber micropulp in a liquid component and discloses that liquid component can be an aqueous liquid, one or more liquid polymers, one or more solvents, or a combination thereof.